Generally, there are two ways to measure an author's impact:
create a citation report listing each work with a citation count;
calculate an index score that assigns a numerical value to the overall impact of an author's publications.
These methods are not exclusive. A citation report can identify specific works with high impact and provide an easy way to list both total works and total citations. An index score can illuminate nuances missed by a citation count (for example, the recency of citations).
These tools measure citations within "traditional" publishing (books, articles, published papers):
iCite provides citation metrics for PubMed articles. Upload a string of PMIDs, and get a variety of metrics, including Relative Citation Ratio: "the citation impact of one or more articles relative to the average NIH-funded paper."
Other Tools for Citation Metrics
These tools aggregate and compile data from a variety of sources, including some traditional citation tools and others not listed above.- Some are free but others require a one-time or annual fee (not paid for by the Library).
Add publications to your profile, or allow Google to find your publications automatically. (Double-check Google's recommendations; you may often find publications from other researchers with similiar names.)
Click "My Citations" on the Google Scholar home page to get a list of articles, citation counts, and graphs.